Class 3 - Flammable Liquids

The word ‘flammable’ means ‘will burn’, so a flammable liquid may be described as a liquid which will burn. However, it is not the liquid itself that burns but the vapour released from the liquid. It needs a source of ignition and to be mixed with air or oxygen in the right proportions.

Flammable liquids make up more than 50% of all dangerous substances moved by road in the UK.

Physical Properties:

Flammable liquids have several physical properties which further categorise them.
Flash-point: this is the lowest temperature of a liquid at which it gives off enough vapour to form a mixture with air that can be ignited by a flame or spark. A low Flash-point indicates a high flammability.
Volatility: this is the readiness with which a liquid changes to a vapour. Normally, high volatility and low flash point go hand in hand.
Miscibility: If a liquid is miscible, it can be mixed with water. If it is immiscible then it cannot be mixed with water. Most flammable liquids are lighter than water. They float on top of water. Miscibility information is required for the emergency services, so that they know how they would deal with a spillage.

Interesting fact:
Did you know that an empty drum of petrol is more hazardous than a full drum of petrol?

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